Quantum physicists at the Massachusetts Institute of Technology believe it is possible to create a time machine which could affect the past without creating a "grandfather paradox".

Scientists have for some years been able to 'teleport' quantum states from one place to another. Now Seth Lloyd and his MIT team say that, using the same principles and a further strange quantum effect known as 'postselection', it should be possible to do the same backwards in time. Lloyd told the Technology Review: "It is possible for particles (and, in principle, people) to tunnel from the future to the past."

The article is cheapened by the "Back to the Future" still. Why is it now "obligatory" for supposedly serious science articles to include pop culture references?

There are those that say that if time travel was possible, we would already have seen visitors from the future. Then again, our current world must seem so prehistoric and harsh to peoples of the future. After all, if it were possible today to travel back to say, the Middle Ages, would anybody actually want to go there?

Someone gave an interesting insight into the problem with time travel.

When you go into the past or future, the physical space around you isn’t still. The universe is expanding, the Sun tugs the Solar System at breath-taking speed into the Milky Way, which too is in rapid motion. One second of time travel implies a change in your physical position to such an extent that you would be over a million miles away from where you were in the “present”.

And harder to keep up with! I used to be ahead of the curve on almost everything, could always see a use for every new piece of technology that came along. But now I can’t. I mean, what’s the use of Twitter? Or music on your phone?

I've thought of the same thing. Even the rotation of the earth must come into play. For example, if I could time travel to 12 hours ago, my physical location might well be somewhere in Asia (not even considering the variables you just mentioned). So any "time travel machine" would have to also make the necessary corrections for physical location - not only in the universe but for movements in the galaxy, solar system and even the rotation of the earth (and the shifting of continental shelves).

The more you think about time travel, the more difficult and complex it becomes.

I think then you should use a spaceship of some sort. With computers we should be able to calculate where in this solar system we would be and what part of the galaxy and what part of the universe, etc. By the time time travel was actually possible that would likely be the best way.

"It is possible for particles (and, in principle, people) to tunnel from the future to the past."

Don't you just love modern physics! If the math works ("and, in principle, people") then it is true! Never mind that the math works for "light is a wave" and at the same time, the math works for "light is a particle". Of course, sometimes it is necessary to throw 11 dimensions into the equation to get it to come out correctly. Kind of like cheating?

Jimmy obviously got his units of measurement, but it is interesting to recall that we are moving at very great speeds. Trying to figure out the effects of our inertia on a time traveling particle would be present several interesting paradoxes. The universal frame of reference sorta means that Galileo was wrong, and the Catholic Church was correct.

(The Catholic Church did not teach the Earth was at the center of a shell of spheres; that was Johannes Kepler, AFTER Galileo, trying to make sense of heliocentrism. The Catholic Church’s position was NOT that the Earth was at the center of the universe, but that the universe was so vast as to approach infinity, and that therefore, any arbitrary point might be regarded as the center of the universe. By Keppler’s time, the Church was regarded as wrong, inasmuch as the Earth revolved around the Sun, rather than the other way around. (And of course, later, that the sun revolved around the Galaxy, the galaxy around teh supercluster...) But the stationary frame of reference, taken to the extreme that one cannot suppose any inertia, would argue that it is not more correct to say that the Earth revolves around the Sun than to say that the Sun revolves around the Earth, bringing us back to exactly Cardinal Nicusa’s “doctrine.”

Obviously they have not been successful in completing the experiment yet in the future as they have not sent anything back congratulating themselves on a job well done.

Or maybe they did come back, but since there is no possibility of a paradox we didn’t realize they were back here, but they were successful, even without tangible results, and therefore should be given a gazillion dollar grant to continue studying this theory.

31
posted on 07/26/2010 7:46:11 AM PDT
by commish
(Freedom tastes sweetest to those who have fought to preserve it.)

Oh good! They need something to rescue the piece of crap final episode of Series 5 of Doctor Who, “The Big Bang”. I count at least three full-on temporal paradoxes, so maybe this new time machine will help. And re-booting the Universe like it was a machine? Even Einstein said the universe did not contain the information required to account for what we see. Good grief.

33
posted on 07/26/2010 8:25:29 AM PDT
by backwoods-engineer
(There is no "common good" which minimizes or sacrifices the individual. --Walter Scott Hudson)

I agree. Ancient Rome, about 29 AD, then a few hops to determine exactly when The Sermon on the Mount occurs. I will learn enough Greek to be able to speak to my Lord Jesus, and to hear Him say, “O ye of little faith! Did you really have to build a time machine to come and see me? Blessed are those who have not seen, and yet have believed!” To which I would reply, “I would have built 10 time machines just to walk the road with You.”

34
posted on 07/26/2010 8:32:20 AM PDT
by backwoods-engineer
(There is no "common good" which minimizes or sacrifices the individual. --Walter Scott Hudson)

Was watching a show on the Science Channel last week and they made the point that the dimension of time really does have all the properties of the other three spatial dimensions (except for our inability to travel at will within it).

Upon hearing this, I immediately had an Aha! moment with respect to the issue you guys are talking about. Of course, a physicist might say it was a snuffle, chortle, bwahaha! moment.

But here is my insight anyway, for your amusement:

Gravity doesnt take a vacation on objects moving in 3-D space and it wouldnt stop working on us if we were traveling in time either. As long as we didnt attach a rocket to our time machine, gravity and Newtons first law would guarantee our coordinates on the surface of the earth wouldnt change after a trip in our Wellsian time machine and we wouldn’t materialize somewhere out in the vacuum of space.

Why do they think there’s a real “grandfather paradox”? The molecules in your body don’t care about an association you have with someone in the past.
You’ll go right on existing if you kill your grandfather, the universe does not care, it’s just a paradox in our minds.

Observationally, the universe is expanding. Thus for one to go back in time it would seem necessary to shrink the universe in it´s entirety to what it´s radius was at a given time in the past. Or, to go forward, the expansion would seem to have to be accelerated. The energy inputs required for either would seem so large as to be in the limit of infinity. Not to even mention the alignment of every particle, which would seem to have to be precisely as it was in the past, or taking into account any randomness of the future.

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